/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.socket.server.support;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.context.Lifecycle;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.http.server.ServletServerHttpResponse;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.web.HttpRequestHandler;
import org.springframework.web.context.ServletContextAware;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.handler.ExceptionWebSocketHandlerDecorator;
import org.springframework.web.socket.handler.LoggingWebSocketHandlerDecorator;
import org.springframework.web.socket.server.HandshakeFailureException;
import org.springframework.web.socket.server.HandshakeHandler;
import org.springframework.web.socket.server.HandshakeInterceptor;

/**
 * A {@link HttpRequestHandler} for processing WebSocket handshake requests.
 *
 * <p>This is the main class to use when configuring a server WebSocket at a specific URL.
 * It is a very thin wrapper around a {@link WebSocketHandler} and a {@link HandshakeHandler},
 * also adapting the {@link HttpServletRequest} and {@link HttpServletResponse} to
 * {@link ServerHttpRequest} and {@link ServerHttpResponse}, respectively.
 *
 * @author Rossen Stoyanchev
 * @since 4.0
 */
public class WebSocketHttpRequestHandler implements HttpRequestHandler, Lifecycle, ServletContextAware {

    private static final Log logger = LogFactory.getLog(WebSocketHttpRequestHandler.class);

    private final WebSocketHandler wsHandler;

    private final HandshakeHandler handshakeHandler;

    private final List<HandshakeInterceptor> interceptors = new ArrayList<>();

    private volatile boolean running = false;


    public WebSocketHttpRequestHandler(WebSocketHandler wsHandler) {
        this(wsHandler, new DefaultHandshakeHandler());
    }

    public WebSocketHttpRequestHandler(WebSocketHandler wsHandler, HandshakeHandler handshakeHandler) {
        Assert.notNull(wsHandler, "wsHandler must not be null");
        Assert.notNull(handshakeHandler, "handshakeHandler must not be null");
        this.wsHandler = new ExceptionWebSocketHandlerDecorator(new LoggingWebSocketHandlerDecorator(wsHandler));
        this.handshakeHandler = handshakeHandler;
    }


    /**
     * Return the WebSocketHandler.
     */
    public WebSocketHandler getWebSocketHandler() {
        return this.wsHandler;
    }

    /**
     * Return the HandshakeHandler.
     */
    public HandshakeHandler getHandshakeHandler() {
        return this.handshakeHandler;
    }

    /**
     * Configure one or more WebSocket handshake request interceptors.
     */
    public void setHandshakeInterceptors(@Nullable List<HandshakeInterceptor> interceptors) {
        this.interceptors.clear();
        if (interceptors != null) {
            this.interceptors.addAll(interceptors);
        }
    }

    /**
     * Return the configured WebSocket handshake request interceptors.
     */
    public List<HandshakeInterceptor> getHandshakeInterceptors() {
        return this.interceptors;
    }

    @Override
    public void setServletContext(ServletContext servletContext) {
        if (this.handshakeHandler instanceof ServletContextAware) {
            ((ServletContextAware) this.handshakeHandler).setServletContext(servletContext);
        }
    }


    @Override
    public void start() {
        if (!isRunning()) {
            this.running = true;
            if (this.handshakeHandler instanceof Lifecycle) {
                ((Lifecycle) this.handshakeHandler).start();
            }
        }
    }

    @Override
    public void stop() {
        if (isRunning()) {
            this.running = false;
            if (this.handshakeHandler instanceof Lifecycle) {
                ((Lifecycle) this.handshakeHandler).stop();
            }
        }
    }

    @Override
    public boolean isRunning() {
        return this.running;
    }


    @Override
    public void handleRequest(HttpServletRequest servletRequest, HttpServletResponse servletResponse)
            throws ServletException, IOException {

        ServerHttpRequest request = new ServletServerHttpRequest(servletRequest);
        ServerHttpResponse response = new ServletServerHttpResponse(servletResponse);

        HandshakeInterceptorChain chain = new HandshakeInterceptorChain(this.interceptors, this.wsHandler);
        HandshakeFailureException failure = null;

        try {
            if (logger.isDebugEnabled()) {
                logger.debug(servletRequest.getMethod() + " " + servletRequest.getRequestURI());
            }
            Map<String, Object> attributes = new HashMap<>();
            if (!chain.applyBeforeHandshake(request, response, attributes)) {
                return;
            }
            this.handshakeHandler.doHandshake(request, response, this.wsHandler, attributes);
            chain.applyAfterHandshake(request, response, null);
            response.close();
        } catch (HandshakeFailureException ex) {
            failure = ex;
        } catch (Throwable ex) {
            failure = new HandshakeFailureException("Uncaught failure for request " + request.getURI(), ex);
        } finally {
            if (failure != null) {
                chain.applyAfterHandshake(request, response, failure);
                throw failure;
            }
        }
    }

}
